The invention relates in general to lined anti-armor munitions, such as shaped charges and explosively formed projectiles (penetrators), and in particular to anti-armor munitions that comply with insensitive munitions standards.
Since the invention of gunpowder and explosives and their application to the conduct of war, the prevention of accidental explosions has been a priority for armed forces concerned with preserving their own safety while handling munitions. This concern is heightened when munitions are subjected to various threat stimuli encountered during their lifecycle. Munitions that do not detonate when subjected to these threat stimuli are known as insensitive munitions (IM).
There is a need in the art of munitions design to improve munition response to IM threats, such as fast cook-off, slow cook-off, bullet impact, fragment impact, and sympathetic reaction, as established by MIL-STD-2105, “Military Standard for Hazard Assessment Tests for Non-Nuclear Munitions”. Fast Cook-Off (FCO) refers to the condition in which the munitions are completely engulfed by the flame from a liquid fueled fire of at least 1,600 degrees Fahrenheit average temperature until a reaction occurs. Slow Cook-Off (SCO) refers to the condition in which the temperature surrounding the munitions is raised at the constant rate of 6 degrees Fahrenheit per hour until a reaction occurs. These tests are meant to replicate accidental exposure to similar conditions in the theatre of war and supporting logistics.
Several methods have been employed in the past to augment or improve various armaments' insensitive munitions performance. While some methods have been developed for application to bombs and warheads, the majority of the prior art includes safety devices for rockets. Of these prior examples, some safety devices rely on purposely creating weakened portions of the casing so that the casing will fail at a predetermined pressure below the pressure at which the explosive material will detonate. But, even though the explosive material does not detonate, the failure of the casing may allow the high pressure in the casing to propel or project damaging fragments outside of the casing.
Other safety devices are activated by a rise in ambient temperature near the warhead. These safety devices typically feature a meltable linkage at the juncture of adjacent sections of the munitions or vent holes covered by a meltable material, both of which are designed to melt at a temperature below the auto-ignition temperature of the explosive material and allow for release of the built-up pressure and evacuation of the products of combustion.
The aforementioned devices are generally complicated in nature and introduce a plurality of related components which present an increased risk of failure of the devices and high production costs associated with the manufacture and complicated assembly methods of the devices. Furthermore, these systems typically require significant redesign of current warhead casings.
A need exists for safety devices for shaped charged munitions and explosively formed projectiles that can achieve improved IM performance without significant negative impacts on functional performance or lifecycle cost.